摘要：

Although the initial isolation of P aeruginosa from sputum may be intermittent in cystic fibrosis and other forms of bronchiectasis, once chronic infection is established it is rarely possible to eradicate it even with intensive antibiotic therapy.5 6 10 11 A number of longitudinal bacteriological studies of cystic fibrosis patients have shown that most of them harbour the same P aeruginosa clone for many years.12-14 Once a particular clone has colonised the lung DNA fingerprinting may reveal shifts in the macrorestriction fragment patterns, indicating subclonal variation, which may result from sequence alterations in restriction recognition sites, genomic rearrangements, and incorporation of extrachromosomal DNA—for example, from bacteriophages.15 Available evidence suggests that acquisition of P aeruginosa is commonly from the environment, but that patient to patient spread can occur particularly if contact density is high such as can occur at cystic fibrosis centres and recreation camps.15-17

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